We arrived at the red carpet around 8:40 p.m., and VIPs started coming in at 9. Designer Marc Bouwer, who has been coming to Klum's celebration for years, was one of the first to arrive. Bouwer and his guest were decked out in lavish gold-shimmering costumes from head to toe. We immediately knew we were in for some crazy costumes that evening.

Sarah Jacobs

Not everyone was dressed elaborately — some opted for simpler costumes, like this cat and maid.

Sarah Jacobs

Christian Siriano, designer and winner of "Project Runway" Season 4, showed up early on with boyfriend Brad Walsh. The two were dressed as Picasso paintings, adorned in painted faces and picture frames.

Sarah Jacobs

According to Siriano, the costumes took about a week to create, even with a team of interns to help sew and put them together. Though Siriano's outfits were tricky, he referred to Klum as "an artisan" in the Halloween world.

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On the left here is Jay Manuel, makeup artist and director of photo shoots on "America's Next Top Model," dressed as a samurai. June Ambrose, celebrity fashion stylist and costume designer, is on the right, wearing an elaborate geisha costume.

Sarah Jacobs

Manuel had the same designer who created Lady Gaga's gloves for the new season of "American Horror Story" make unique gloves for his costume, complete with sharp nails. "This is the one night I get to go crazy," Manuel, who has been coming to Klum's party for five years, told Business Insider.

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Singer and songwriter Tinashe, who wore a Snoop Dog costume, told Business Insider she wanted to "bring the West Coast" to New York City for Halloween. She added that she had to go all-out with her getup since Klum is known for setting the bar high. This was Tinashe's first year being invited to the party.

Actress Diana Guerrero from "Orange Is the New Black" and her guest were dressed as Tina Belcher and Bob from the cartoon "Bob’s Burgers." "Halloween is my favorite holiday by far," Guerrero told us. "I absolutely love seeing the crazy costumes Heidi's party always brings out, and it's always fun to see people dressed as 'Orange Is the New Black' characters."

Sarah Jacobs

Her fellow "Orange Is the New Black" costar Jackie Cruz and her guest were decked out as Priscilla and Elvis Presley. "I love Elvis' music and style," Cruz told us. "I get my costume custom-made every year to make sure it stands out." Her favorite Klum costume was the elderly woman getup she donned in 2013, which also happened to be the first time Cruz met the supermodel.

Sarah Jacobs

Dacha Polanco from "Orange Is the New Black" was also present with her stylist. She was dressed in a "Pretty Woman" costume, which, she told reporters, caused "several wardrobe malfunctions earlier in the day." The "Orange Is the New Black" stars would be sitting at a reserved table inside.

Sarah Jacobs

As celebrities arrived outside Lavo in their cars, paparazzi would jump to try and grab their photo before their red-carpet walk. Here, Irina Shabayeva, winner of "Project Runway" Season 6, flashes a shimmering Vegas-inspired look.

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Actor Eric West showed up in a casual 1970s-inspired ensemble.

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Jamie McCarthy and Megan Thompson were dressed as The Joker and Harley Quinn.

Sarah Jacobs

Kelly Bensimon wanted to be "the ultimate American girl" and went as Minnie Mouse.

Sarah Jacobs

Many of the attendees were models, like couple Hailey Clauson (left) and Jullien Herrera (right), who dressed as pirates. Clauson, who picked up her costume from a Gothic shop, said she predicted Klum might be dressing as Amber Rose. "I love coming because of how realistic Heidi gets with her costumes ... it's like full-on movie magic with her," Clauson told reporters.

Model Nina Agdal was also there in a neon-blue superhero-inspired costume, complete with a battery-powered star belt. "Heidi nails it every time, but you have to bring it yourself, otherwise you're not getting let in," Agdal said.

Sarah Jacobs

Model Georgina Burke was also present, dressed as Ursula from "The Little Mermaid."

Actor Kyle MacLachlan and wife Desiree Gruber were also in attendance. Gruber joked that she had wanted to dress in a hamburger costume, but ended up going with this look instead. MacLachlan said that he's been coming to this event for almost 15 years.

As we waited for the final celebrities to arrive close to 11 p.m., we heard that Jennifer Lopez and Heidi might arrive at the same time. First, Jennifer Lopez graced the red carpet in an elegant skeleton outfit and piercing contacts.

Sarah Jacobs

Before we knew it, a single spotlight turned on, music started to play, and Heidi herself appeared from between two curtains, dressed in a Jessica Rabbit costume. Dancing and singing Jessica Rabbit's famed "Why Don't You Do Right" song from "Who Framed Roger Rabbit," Klum danced around the red carpet as the crowd watched in excitement.

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"Jessica Rabbit is definitely an icon and I always try and find someone that people will know and recognize,” Klum told reporters as she described why she chose the costume. She decided on the getup eight months ago and even went into a studio to record her version of the Jessica Rabbit song.

Sarah Jacobs

Klum explained that it it took most of the day to put the costume on — from about noon until her arrival at the party — and that it takes about an hour and a half to take it off. Since it was so difficult to put on, Klum had to wing her dance performance, as she couldn't practice in the costume beforehand.

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After her performance, Klum posed with model Gigi Hadid, who was dressed as Sandy from "Grease."

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As we entered through the celebrity entrance of the club, we were surprised by frightening decor on the walls. "The Twisted Twins" — Sylvia and Jen Soska from GSN's show "Hellevator" — greeted guests, cackling, "Welcome to Heidi Klum's Halloween party. Ready to play?"

Business Insider/Talia Avakian

As we made our way down the corridors, we were surprised to see two little girls dressed in ghostly makeup following us down the halls.

Business Insider/Talia Avakian

There was even a "doctor" with a fake bloody organ in his hand.

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Inside, Klum gave one more performance of her version of "Why Don't You Do Right" before giving the floor to DJ Questlove.

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Questlove played everything from disco and 1980s music to swing and the latest in pop.

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The crowd rushed to snap selfies with Klum, who would later be seated in a VIP section.

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The VIP area was where guests like Jennifer Lopez, Casper Smart, Gigi Hadid, and Klum were seated.

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But some celebs, like the cast of "Orange Is the New Black" and Ashanti, who was dressed as a Smurf, could be spotted sitting at tables on the dance floor.

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Performers decked out in shiny costumes could be seen scaling the sides of the dance floor.

Talia Avakian

Decorations in the club included an array of ghoulish carved pumpkins.

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After midnight, the event turned into a club night that was open to those who had bought tickets, which cost from $60 to $175, with a minimum of $2,000 for bottle service. Around 1:30 a.m., the club started getting packed.

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But even on our way out around 2 a.m., we still managed to spot some of the most stunning elaborate costumes of the night.